Experiments are designed to determine whether immune cells and/or antibodies to tumor-specific plasma cell antigens (idiotypic determinants of myeloma proteins) act in a cooperative or antagonistic fashion to mediate tumor cell destruction. Immunoadsorbent purified anti-idiotypic antibodies will be examined for the presence of antibody that can bind to tumor cells and the role of antibody in suppressing tumor growth will be analyzed by passive administration of antibody. Cellular immunity will be studied in vitro by lymphocyte- and antibody-mediated lymphocytotoxicity tests using myeloma cells incubated with cyclohexamide and treated with glutaraldehyde to get around the possibility that secreted antigen may be interfering with assay procedures.